Flotation process and apparatus.



1. A. PEARCE.

FLOTATION PROCESS AND APPARATUS.

APPLICATION H LED MAY 29, I911- 1,277,750. Patented Sept. 3,1918.

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- FLOTATION PROCESS AND APPARATUS.

APPLICATION FILED MAY 29, I911.

IIII- n [p l IL k0 O Patented Sept. 3, 1918.

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JACKSON A. PEARCE, OF'IDAHO SPRINGS, COLORADO.

FLOTATION PROCESS AND APPARATUS.

. Specification of Letters Patent.

Patented sent. 3, 1918.

Continuation of application Serial No. 147,699, filed February 9, 1917.This application filed May 29, 1917.

Serial No. 171,649.

To all whom it may concern:

Be it known that I, JA'oKsoN A. PEARCE, citizen of the United States,residing at Idaho Springs, Clear Creek county, and State of Colorado,have invented certain new and useful Improvements in Flotation Processesand Apparatus; and I do declare the following to be a full, clear, andexact description of the invention, such as will enable others skilledin the art to which it appertains to make and use the same, referencebeing had to the accompanying drawings, and to the characters of'reference marked thereon, which form a part of this specification.

My invention relates to a process and apparatus for the separation ofmineral values on the flotation principle, oil or other substance beingmingled with the pulp and acting in combination with air bubblesto causethe mineral values to rise to the top whereby they may be skimmed off asa sort of froth.

In my improvement I employ a series of chambers each of which is dlvidedby a partition into a receiving and a separating compartment, the bottomof the receiving compartment having an opening to allow the pulp to passtherethrough, after which it is acted on by an impeller which for ces itthrough an opening in communication with the separating compartment,into the bottom of the latter compartment, the im-,

peller serving to maintain the receiving compartment practically empty-while the separating compartment is kept full, provision being made toallow the pulp to overflow from the separating compartment into anadjacent receiving compartment, thus preventing as far as possible anygangue ,Or comparatively barren pulp from passing with the mineral frothinto the launder which receives said froth.

By virtue of the fact that the receiving compartment is kept practicallyempty, the pulp has a considerable fall both as it overflows into thereceiving compartment from an adjacent separating compartment, and

5e impeller below the bottom ofthe receiving also when originally fedinto the receiving compartment. During this fall from the top to thebottom of the practically empty receiving compartment, air is entrainedor caught by the pulp and carried downwardly therewith. Furthermore therotation of the compartment, produces suction whereby air is furthermingled with the pulp as it is forced into the bottom of the separatingFigure 1 is a vertical section taken through the apparatus on the linel1,

Fig. 2 is "a top plan view in detail of the impeller shown on a largerscalethanin Figs. 1 and 3.

Fig. 3 is a top plan View of the apparatus.

Fig. 4 is a side elevation of the impeller shown on the same scale asFig.2.

The same reference characters indicate the same parts in all the views.

Letthe numeral 5 designate a casing considered in its entirety, andprovided with a number of partitions 6 separating the easing into anumber of chambers 7 each of which is divided by a partition. 8 intoreceiving and separating compartments respectively, designated 9 and 10,each pair of which may for convenience be designated a unit. Thereceiving compartment has a bottom 12 which i supported somewhat abovethe bottom 13 of the casing, leaving a space 14 between the parts 12 and13. This space is in communication by-an opening 15 with the bottom ofcompartment 10, the latter being provided with an inclined wall 16,which extends downwardly from the top of the compartment and joins thehorizontal bottom 13 of the casing as shown at 17.

In the space 14 between the bottoms 12 and 13 is located an impeller 18which is rotated at any desired speed through the medium of a verticallydisposed shaft 19 which is journaled in across piece 20 supported abovethe compartment 9. This shaftcompartment empty. It will be understoodfrom what has ,already been explained that by rotating the impeller 18at the desired speed, the pulp may be removed from the receivingcompartment as aforesaid into the separating compartment, practically asfast as it enters the receiving compartment, thus maintaining a part ofthe opening 22 in the bottom 12 sufficiently free to permit a relativelylarge quantity of air to be sucked therethrough with the pulp as thelatter is drawn downwardly byreason of suction developed by thecentrifugally acting impeller.

Within the separating compartment, I arrange a number of deflectors orblades which have a tendency to cause the gangue as it passes upwardlyin the receiving compartment, to move toward a short trough 2 1 which issunk into the partitions 6 and 8 at their intersection, the bottom ofthe trough being on a proper level to receive the overflow from anyseparating compartment and deliver it to an adjacent receivingcompartment as best. illustrated in Fig. 3. These blades constitutebaffles and are respectively designated by the reference characters 23and 23 (see Fig. 1.) If it is desired to. deliver the overflow to aremote receiving compartment, an additional trough 25 may be employedwhich extends above the top of an adjacent receiving compartment anddirects the overflow into a remote receiving compartment as ustexplained.

. In this way oneor more recelvinggcompartments may be cut out, so tospea and the overflowfrom any separating compartment delivered to anydesired recelving compartment.

As shown in the drawing, two launders 26 and 27 are supported adjacentthe casing 5 on the froth discharge side, the froth 28 being removedfrom the top of the receivink compartment by a rotary skimmer 29 ofsuitable construction. In case the froth is dirt or not sufiicientlyclean it may be desire to return it for re-treatment and in this event abridge 30 may be placed ontop of or over the launder 26, the same beingof suflicient width to direct the froth into the launder 27. Thisbridgeis removable and "may be employed in connection with any separatingcompartment, and should be used if it appears that the froth as itleaves any separating compartment is not suffi-v ciently clean forcommercial purposes. a

This application is a continuation of my prior application, Serial #1 17,699, filed Februar 9,1917. The apparatus as illustrated dlscloses abattery or set of chambers 7 each divided by partitions 8 into receivingand separating compartments. From this it will be understood that theoverflow pulp may be subjected to any desired numer of treatments sinceas it leaves theffirst separatmg compartment, it may pass to the secondreceivin compartment and so on whereby it is subjected to any desirednumber of treatments, the construction being such that the pulp ispractically completely impoverished of the originally contained mineralvalues. 7

As illustrated in the drawing, the pulp, which it may be assumedcontains a suitable proportion of oil, is fed as shown at 31 into thereceiving compartment 9 of the first chamber and passes thence into theseparating compartment 10 of the same chamber, from which it overflowsinto the second receiving compartment 9 and so on. Or, if the additionaltrough 25 is employed, the overflow may be carried to a remote receivingcompartment as heretofore explained.

From the foregoing description it is believed the invention will bereadily understood. The falling of the pulp as it is orig inally fedinto the first receiving compartment 9, downwardly into the bottom ofsaid compartment, naturally entrains as heretofore indicated,considerable air and as it is sucked through the opening 22 into thespace below by the action of the impeller, a relatively large quantityof air is mingled therewith in the form of bubbles and unites with theoil to gather the mineral values on the well-known flotation principlewhereby they are caused to rise to the top of the separating compartmentand removed in the form of froth in a manner that will be wellunderstood. In this application Idesire to emphasize the feature wherebythe pulp is delivered into a substantially empty receiving compartmentwhile the adjacent separating compartment in communication therewith atthe bottom, is kept full by the centrifugal action of the impeller orany other desired form of pumping apparatus, thus greatly facilitatingthe mingling with the pulp of the necessary air and contributing in animportant degree to the eflective separation of the mineral values fromthe pulp in the receiving compartment and to flexibility of operation.

Attention is called to the fact that the material to be treated is fedinto the separating compartment at a lower level than the discharge fromthe separating compartment. In other words, in my improvement thetailings as well as the mineralized froth are discharged from the top ofthe separating compartment. By having the feed into the separatingcompartment lower than the discharge from said compartment, there is agreat advantage due to the fact that by this arrangement there. isalways a considerable fall between the top of the separating compartmentand the point of feed to said compartment, thus making it unnecessary toautomatically accomplished due to the fall from the pointof discharge tothe point of eed, speaking with reference to the separating compartment.v

I wish to emphasize the importance of the overflow discharge of thetailings at the top of the pulp in the separating or flotationcompartment at approximately the same level as the froth overflow. 1 Ifthe tailings the outlet and the machine, consequently a valve andcareful regulation of the valve are necessary.

Furthermore, in any machine with a discharge below the surface there isa tendency for the coarser particles to discharge in preference to thefiner particles with the consequent accumulation of colloids above thedischarge, including colloidal matter. In my machine, the dischargebeing at the top of the pulp, the tendency is for the colloids todischarge in preference to the coarser particles with a consequentaccumulation of the coarser or granular particles within the machine,.thus raising the percentage of granular material. This is a distinctadvantage in flotation. In the course of a short time this percentagebecomes constant,

the granular and colloidal material over-' flowing in the sameproportion as in the feed.

Besides, the retention of the coarse ma terial in the rising column upto the gangue overflow, subjects the coarse material, in a relativelyquiet region, to the bubbles com- '-ing from the agitation compartmentand enhances the likelihood of values therein be- ,ing caught andcarried into the froth.

aving thus described my invention what I claim is: 1. The hereindescribed flotation process including aerating the pulp, overflowing thefroth, maintaining the tailings in Suspen-- sion by an upwardcirculation of the pulp in a flotation compartment, and overflowing thetailings wholly from said compartment at a substantial distance abovethe inlet and in proximity to the level of the overflow of the froth butseparate therefrom.

2. The herein described flotation process consisting in feeding pulpinto a chamber above the bottom of the latter, aerating and forcing itfrom the bottom thereof into the bottom of another chamber to keep thefirst chamber substantially empty and the sec- 0nd chamber full at thedesired height above the bottom of the first chamber, overflowing thefroth, .maintaining the tailings in suspensionby the upward circulationof the pulp in the chamber and providing for their overflow wholly at asubstantial distance above the inlet, in proximity to the level of thefroth overflow and separate therefrom. 3. A flotation separating unitcomprising an agitation compartment and a flotation compartment having afroth overflow, the said compartments communicating at the the bottom,the flotation compartment being relatively deep and having a tailingsdis charge away from the unit, at a substantial distance above .theinlet and in proximity to the level of the froth overflow, but separatetherefrom, the unit being otherwise closed against the discharge of thetailings.

A flotation separating unit comprising an agitation compartment and aflotation compartment communicating at the bottom, the flotationcompartment being relatively deep, provided with a froth overflow andhaving a tailings discharge away from the unit, at a substantialdistance above the inlet and in proximity to the level of the frothoverflow, but separate therefrom, the unit being otherwise closedagainst the discharge of the tailings, means for feeding the pulp intothe agitation compartment above the bottom, means for forcing the pulpfrom the bottom of the agitation compartment into the bottom of theflotation compartment, said last named means being adapted to beoperated to maintain the agitation compartment substantially empty andthe flotation compartment full, and means for removing the froth fromthe upper part of the flotation compartment.

5. Flotation apparatus comprising a plurality of flotation separatingunits each composed of an agitation compartment and a flotationcompartment, the flotation compartment of each unit except the lastbeing arranged to have a tailings overflow from its own unit into theagitation compartment of another unit, such overflow being at asubstantial distance above the inlet to the flotation compartment andapproximately at the level but separate from the froth overflow, thedelivery to the agitation compartments being spaced a considerabledistance above the normal pulp levels therein to provide a substantialdrop through air, the agitation and flotation compartments of each unitbeing in communication at the the pulp from the bottom of the agitationcompartment into the bottom of the flotation compartment.

6. Flotation apparatus including a cham ber divided into anagitationcompartment and a relatively deep separating compartment incommunication at the bottom with the agitation compartment, providedwith a froth overflow, and having a'gangue overflow at a substantialdistance above the inlet and in proximity to the level of the frothoverflow, the chamber or unit being otherwise closed against thedischarge of gangue.

7. Flotation apparatus including a chamberdivided into an agitationcompartment and a relatively deep separating compart ment incommunication at the bottom with the agitation compartment, providedWith a froth overflow and having a gangue overflow at a substantialdistance above the inlet and in proximity to the level of the frothoverflow, the chamber or unit being'other- Wise closed against thedischarge of gangue, means for feeding the pulp to the agitatingcompartment above the bottom, means for forcing the pulp from the bottomof the agitating compartment into the bottom of the separating vcompartment,. said last named means bein adapted to be operated tomaintain the agltating compartment substantially empty and theseparating com-' partment full, and means for removing the froth fromthe top of the pulp in the separating compartment.

In testimony whereof I afiix my signature.

JACKSON A. PEARCE.

